Telephone system



Nov. 28, 1939. LEWIS 218L191 TELEPHONE SYSTEM Filed Dec. 16, 1938 2 Sheets-Sheet l I /7 2o w a 2/ 2 /s 9 4 2a,24&25

INSULATION 2 INVENTOR h. A. LEW/S ATTORNEY Nov. 28, 1939. H; A, LEWiS 21 L1 TELEPHONE SYSTEM Filed Dec. 16, 1938 2 Sheets-Sheet 2 sue FIG. 3

W ANOTHER LINK lA/vs/vrok By H 14. LEMS wwm g ATTORNEY Patented Nov. 28, 1939 UNIT-ET TELEPHONE SYSTEM Herbert A. Lewis, Baysi'de; N.

Laboratories,

Bell Telephone Y., assignor to Incorporated,

New York, N. Y. a corporation of New York Application December 16. 1938, Serial No.

7 Claims.

This invention relates to telephone systems and particularly to the improvements in the mechanism for establishing connections between subscribers lines at an exchange.

An object of the invention is to simp-lity'and improve the mechanism and circuits employed by the operators at an exchange for establishing telephone connections.

Heretofore systems have been provided" for establishing connections between subscribers" scribers holding bar to connect the calling line to the calling branch ofa preselected link and then actuates the called subscribers holding bar I to connect the called line to the called branch of. this link.

A system of this kind is disclosed in my Patent 2,107,158 of February 1, 1938 which relates to means whereby when the calling subscriber and the called subscriber replace their receivers on the switchhooks, lamps gaged link and whereby the operator can then actuate a key in the engaged link to flash the line lamps to identify the engaged subscribers lines with the engaged the connection by manually releasing the associated engaged holding-bars. I

The present invention has been disclosed in."

connection with the system of the above-mentioned patent and a patentable feature thereof is an arrangement in said system whereby when a connection has been established between a calling subscriber and a called subscriber, the operator may identify the engaged link or the connected subscribers with each otherby turning a knob or cap associated with either the; calling subscribers or the called subscribers holding bar which causes a circuit arrangement to be opera ated to, actuate the corresponding signal'lamp in the calling or called branch of the engaged link to identify it.

The invention has been illustrated in the accompanying drawings in which:

Fig. 1 is a fragmentary side section of the cross-bar switch structure as disclosed in the above-mentioned patent in which the applicantsinvention has been incorporated; I

be associatedlinks with se- Each of said holding bar comprising .6 and I, connected together at one endby an are lighted in the entherein pulled outis link so that she may release,

with the spring v v be made between the ringstrip l a'ndthe contact view in cross.-

Tms Artur OFFICE Fig. 2 is a fragmentary plan" view of this switch structure; and

Fig. 3 isacircuit arrangement as disclosed in the above-mentioned patent with the applicants invention incorporated therein with the crossbar switches in accordance with Figs. land 2 shown in diagrammaticform.

Referring .now to the drawings and particue larly toFigs; .1 and 2, each end of a link is represented by three strips I,2 and 3 insulated from each other and the selecting bars associated therewith are shown in the form of fiat bars 4, while each subscribers line is represented by a threeadjacent strips 5,

insulating piece 8 which in turn is connected to a plug 9 in a socket" Iii and in which'is located a subscribers line lamp H. An electrical connection may be made through one ofthe holding bars, for example, the sleeve 5 to a contact 12 at the rear of the switch when. the holding bar is in normal position. One terminal of the lamp llmay be connected to this sleeve strip 5 and the other terminal connected to plug s which makes contact with the plate It in front of the structure which in turn may be connected to ground. ,Theterminalof the lamp .6 l connected to the sleeve strip Smay also be connected to a spring l4 while a spring 15 may beconnected to battery so that when the plug, 9 with the lamp I I through the socket iii and the lamp It and the surrounding sleeve it or knob are turned manually, in a counter-clockwise direction, the pin will rotate in a slot I! attached to the sleeve 56 in socket ill to engage the Hand move it to make electrical contact l5. Another connection may also spring It to battery when the position. The purpose selecting bar is in normal of. these various connections between contacts I4 and i5 and at'l2 and 18 will be apparent as the description proceeds.

The link strips l, 2 and 3 are, provided with downwardly extending hooks 28, 2t and 22 which are bent at their ends in a common horizontal plane. The holding bars 5, 6 and l are provided with hook members 23, 24 and 25 for engagement withthe hooks 2!), 2i and 22 respectively, at the cross-points of the'selecting andholding bars in a manner as will hereinafter be described.- It should be noted-that a plurality of cross-bar switches such as described, have been shown in a drawing with one switch on top of the other and there may be any number of such switches arranged in this manner in an exchange depending only on the number of lines terminating therein. There may, for example, be ten switches horizontally arranged one on top of the other and each switch may have ten subscribers line holding bars. The link strips of the various switches may be strapped together in a manner illustrated in Fig. 3, that is two adjacent links in each switch are connected with the two corresponding ones of all the other. switches arranged above or below them. The selecting bars associated with the link strips are similarly connected together by vertical bars shown in diagrammatic form. in Fig. 3 and indicated by the numeral 28 for the first link which is operated by solenoids 22 and 39 to rotate the connected selecting bars 4 or tilt them for the purpose of selecting as will hereinafter be described.

This mechanism operates as follows. If, for example, the magnet 33 associated with the last line illustrated in dotted lines in Fig. 1 has been operated, the bar 3%, also illustrated in dotted lines in this figure, causes the selecting bars 35 to 38 to be turned to the position shown and then plug 9 at till, for example, is pulled out toward the left by the operator, the projections 23, 24 and 25 at ll will be raised due to the lower humps on these projections and then lowered to a position where they will contact respectively with the hooks 29, 2i and 22 on the link strips at 43. A connection will therefore be established from a calling subscribers line connected to the holding bar associated with the plug at Qil to the link strip at i l. These link strips may be named calling link strips. In a similar manner a called subscribersline may be connected through a holding bar to the companion link strips that may be named called link strips. It should be understood that as soon as the calling link strips have been connected,'the bars 4 of these links will be restored to normal and the selecting bars 4 of the companion called link strips will be automatically tilted so that the called line strips will be connected with the called link strips of this link, when the called line plug is pulled out. It should be observed that the selecting bars 35, 36 and 38 will not disturb the projections 23,- 24 and 25 on other bars, as for example, in the case of bars at 5 which have already been operated. There is room enough for the selecting bar 35 to move into the tilted position shown due to the upper humps of the projections 28, 24 and 25 of this bar. Similarly in case of the selecting bar 35, the projections on the bars at 46 which have not been operated will not be disturbed due to the normal positions of the projections 23, 24

and 25.

Referring now to the operation of the circuit as shown in Fig. 3, it will be noted that the link circuit shown at illil terminates in a calling end in the tip, ring and sleeve conductors at it! multipled to the corresponding calling link tip, ring and sleeve strips of the diiferent layers of switches, the upper and low er of which have been shown in diagrammatic form. This link circuit also terminates in the called end in tip, ring and sleeve conductors at :02 multipled to the'corresponding called link, tip, ring and sleeve strips of the different layers of switches. A connection from a calling subscribers line such as Hi3 may therefore be extended through contacts at the cross-connecting point not through the calling end of the link circuit at liiil, and over the called end of the link through, for example, a crossconnection point I65 to a called subscribers line lfiil. The link 5% is shown as the first link in H and upper armature and back contact of relay HI through the winding of magnet 29 to ground.

If now the subscriber of line Hi3 removes his receiver from the switchhook, lamp H2 of this line will be lighted over a circuit from battery, contacts l8 associated with the ring strip over the ring conductor through the loop of the call ing subscribers station, back over the tip conductor through contacts l2 over the sleeve strip through the lamp H2 to ground. This indicates to the operator in attendance that this subscriber desires to make a call. She consequently pulls out the plug 9 of this calling subscribers line bar and thereby establishes a connection between the tip, ring and sleeve strips of this line and the corresponding tip, ring and sleeve strips of the calling end of link Hill at the cross-connecting point H14. This connection at M4 is established in the manner described in connection with Figs. 1 and 2. In pulling out this plug, lamp H2 is extinguished as the connections through contacts l2 and I8 are opened. Relay l H is now operated from battery and ground through its windings, tip and ring conductors of the calling end of the link through the connection at m, the tip and ring conductors and the calling subscribers loop. Relay H I in operating closes a circuit for the lighting of lamp H 3 from battery through the lower armature and front contact of relay l H, contacts of relays H4, H and H0 and lamp H3 to ground. The lighting of this lamp indicates to the operator which link the calling subscribers line is connected to. She consequently operates the talking key H5 and thereby connects her telephone set Ill to the link mo, answers the calling subscriber and receives the desired subscribers number. When relay Ill operated, the circuit hereinbefore traced for magnet 29 is opened at the upper armature and back contact of this relay, and magnet 29 in releasing closes ,a circuit for the operation of magnet 30 from battery, contacts of relays H5 and .l M, winding of magnet 30, contacts of magnet 29 to ground.

This magnet now prepares the selecting bar 4 of the called end of the link I09 for a connection to a called subscribers line. It should, of course, be understood that the proper subscribers num-- ber may be marked on the front of the plate l3 or on individual plugs for each subscribers line. Consequently, the operator may now search for the called subscribers number and when found pull out the corresponding plug 5*. In this case the one leading to the subscriber of line I06 may be chosen. This causes a connection to be established at the cross-connecting point I05 between the called end of the link over the tip and ring and sleeve conductors and the called subscribers line me. The connection for the sleeve conductors causes the operation of relay H5 from battery, contacts of relay H4, winding of relay H 5, sleeve conductors, point I05 and lamp l22 to ground. The lamp l22 does not receive sufiicient current at this time to cause it to light due to the resistance of the winding of the extinguishing of lamp H3.

mal. The magnet 31} now closes at its armature and back contact a circuit to ground for the Y preselection of the magnet for the calling end of the next link, in this case the magnet 42 may be operated so that this magnet will operate to prepare the next idle link for a call. The operator in observing the lighted lamp I24 knows that the called subscribers line has been connected to the link and will thereiorering the called subscriber by operating the ringing key I26 in the usual manner. When the called subscriber of line 526 answers, the operator restores the ringing key I26 and relayfI I4 operates from battery and ground through its winding, contacts of the ringing key I26, the connection through the tip and ring conductors over the called end of the link through the point I and the loop of the called subscribers line I95. Relay H4 in operating opens the circuit for relay H5 which releases and extinguishes lamp I24. A connection is now established from the calling subscribers line 403 to the called subscribers line I66 over link I05 and talking batteries for these subscribers are supplied through windings of relays III and H4 and a talking connection through condensers E21 and I28.

' After conversation is finished and, for example, the calling subscriber replaces his receiver on the switchhook', the relay III is released. This re-. lay closes a circuit for the operation of relay IIB. This circuit may be traced from battery through contacts of relay III, winding of relay III the calling end of the link, point I54, lamp H2 to ground. Lamp H2 does not receive suflicient current to light due to the resistance of the winding of relay Ha. Relay IIil in operating closes an obvious circuit for the lighting of lamp .I'I3. This indicates to the operator that the calling subscriber has hung up his receiver.

When the called subscriber hangs up his receiver, relay I'I l is released. This causes the operation ofrelay H5 and the lighting of lamp I24 of a circuit hereinbefore traced. As both lamps H3 and I24 are now lighted, the operator will know that the connection through this link has been relinquished by both subscribers. It is now only necessary to restore the plugs 9 of the calling subscribers line and called subscribers line in the switch in order to release these lines at the points 504 and W5 from the link and thus restore the link to common use. To identify the plug of the calling subscribers line for this purpose, the key I32 is'operated repeatedly toward the left. This applies battery directly to the sleeve for lamp H2 and causes it to flash which identifies lamp H2 as that of the calling subscriber whose line is associated with link I00 and the operator may then restore the corresponding plugs 9 to release'the connection to this subscriber. This causes the release of relay H0 and. The. operator will then operate key I32 toward the right to similarlyflash the lamp I22 of the plug!) of the called subscribers line. When this identification is made, she restores the corresponding plug 9 to normal which opens the connection at point I05 and the relay H5 is thereby restored and the lamp I24 extinguished. The link I00 may now be used for other calls.

The arrangement in accordance with the invention, whereby when a connection has been established between a calling subscriber and a called subscriber the operator may identify the engaged link or the connected subscriber with each other, operates as follows. When the operator desires to make such an identification, she merely turns the plug ,9 of, for example, the calling subscribers line and this closes a connection between the corresponding contacts I4 and I5 of this line in a manner hereinbefore described in connection with Fig. 1. The closing of this circuit'provides the operating circuit for relay I32 from battery through contacts I5 and I4, the connection over the sleeve through points I84, left-hand winding of relay I32 to ground at contacts of relay H4. Relay I32 in operating closes an obvious circuit for the operation of lamps H3 and I24 in the engaged link I20 thus identifying this link as being the one engaged by the subscriber of line I03. Similarly the operator may turnthe plug 9 of the subscribers line Hi6. This closes a circuit from battery through the contacts I5 and I4 over the sleeve conductor through the point I05, right-hand winding of relay I32 to ground at contacts of relay I It to cause relay I32 to operate to light lamps I I3 and I24.

It should also be noted that. regardless of whether the plug of a calling subscribers line or a called subscribers line is turned, the lamps of both subscribers lines are lighted. Thus the two connected subscribers lines may be identified with each other.- If the plug of the calling subscribers line is turned the circuit for the lamp H2 is obvious and the circuit for lamp I22 may be traced as follows upon the operation of relay I32, from battery through contacts it and I5 of the calling subscribers plug, point HM, the sleeve conductor, the left-hand, armature and front contact of relay I32, sleeve conductor of the called subscribers line, point I65, lamp I22 to ground. A similar circuit is provided for the lighting of lamp I I2 in case the called subscribers plug is rotated. In this case the circuit extends from battery through contacts I4 and I5 of the called subscribers sleeve, point Hi5, left-hand armature and front contact of relay I32, the sleeve connection, point IM, lamp H2 to ground. This arrangement of identifying links with the subscribers lines connected thereto or subscribers lines with each other is useful in various types of traffic as, for example, in the case where the line of an executive is busy and a trunk call comes in that requires his immediate attention. In this case the operator should be able to tell with whom he is speaking and thus determine whether or not to break in on the conversation.

What is claimed is:

1 In a system comprising cross-bar switches, subscribers lines, holding bars, links, means for establishinga connection between a calling subscribers line and a called subscribers line over a link through a switch responsive to the automatic selection of two selecting bars and the manual operation of two holding bars, and means responsive to the further manual operation of either of said two manually operated holding bars for identifying the associated link and either of the connected subscribers lines.

2. In a system comprising cross-bar switches, subscribers lines, holding bars, links, means for establishing a connection between a calling subscribers line and a called subscribers line over a link through a switch responsive to the auto-.

matic selection of two selecting bars and the manual operation of two holding bars, a rotatably mounted extension on each of said holding bars, and means responsive to the rotation of the extension on either of said two manually operated holding bars for identifying one with the other and the associated link.

4. In a system comprising cross-bar switches, subscribers lines, holding bars, links, means for establishing a connection between a calling subscribers line and a called subscribers line over a link through a switch responsive to the automatic selection of two selecting bars and the manual operation of two holding bars, signaling means associated with said link, and means responsive to the further manual operation of either of said two manually operated holding bars for operating a signaling means of the associated link to identify it.

5. In a system comprising cross-bar switches, subscribers lines, holding bars, links, means for establishing a connection between a calling subscribers line and a called subscribers line over a link through a switch responsive to the automatic selection of two selecting bars and the manual operation of two holding bars, signaling means associated with each holding bar, signaling means associated with said link, and means responsive to the further manual operation of either of said two manually operated holding bars for operating the signaling means associated with said holding bars and the signaling means of the associated link to identify one engaged subscriber's line with the other and to identify the associated link.

6. In a cross-bar switching system, subscribers lines, selecting bars, holding bars, links, each link having a calling branch and a called branch, means for establishing connections between a calling subscribers line and a called branch of a link and between a called line and the called branch of said link in response to the automatic operation of two selecting bars individual to said link and the manual operation of two holding bars individual to the calling subscribers lines and the called subscribers lines respectively, a signal associated with each branch of a link, means responsive to the further manual operation of the holding bar individual to the calling subscribers line for actuating the signal associated with the calling branch of the engaged link to identify it, and means responsive to the further manual operation of the holding bar individual to the called subscribers line for actuating the signal associated with a called branch of the engaged link to identify it.

'7. In a system comprising cross-bar switches, subscribers lines, holding bars, selecting bars, links, means for establishing a connection between a calling subscribers line and a called subscribers line over a link to a switch responsive to the automatic selection of two selecting bars and the manual operation of two holding bars, means responsive to the further manual operation of either of said two manually operated holding bars for identifying the associated link and manually operable means for identifying the two manually operated holding bars for the restoration thereof to normal to release said established connection.

HERBERT A. LEWIS- 

